Linear heat-hardenable copolymerizate

ABSTRACT

and a methyl group, and R2 is an alkyl group having 1 to 4   carbon atoms,   IN WHICH R1 is selected from the group consisting of hydrogen and a methyl group, and R2 is an alkyl group having 1 to 4 carbon atoms, TWO TO 15 MOLE PERCENT OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF MALEIC ANHYDRIDE AND ITACONIC ACID ANHYDRIDE, AND FOUR TO 15 MOLE PERCENT OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID GLYCIDYL ESTER AND METHACRYLIC ACID GLYCIDYL ESTER. IN WHICH R1 is selected from the group consisting of hydro   This invention relates to a linear heat-hardenable copolymerizate, and to a method of treating a wood surface with a foil of the said copolymerizate, the copolymerizate having a limiting viscosity of Eta 0.7 to 3.0 (100 ml . g 1) measured in toluene at 20* C., and comprising SEVENTY TO 94 MOLE PERCENT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF STYRENE OR AT LEAST ONE MONOMER HAVING THE FORMULA

145 Oct. 23, 1973 LINEAR HEAT-HARDENABLE COPOLYMERIZATE [75] Inventors:Jurgen Foch, Essen-Bredeney;

Ulrich Holtschmidt, Essen, both of Germany [73] Assignee: Th.Goldschmidt AG, Essen,

Germany 22 Filed: Oct. 18, 1971 21 Appl. 190.. 190,393

Related US. Application Data [62] Division of Ser. No. 31,748, April 24,1970, Pat. No.

[30] Foreign Application Priority Data May 6, 1969 Germany P 19 22 942.6

[52] 11.8. C1. 161/232 [51] Int. Cl 1332b 27/10 [58] Field of Search..l6l/23l-233,

[56] References Cited UNITED STATES PATENTS 3,563,953 2/1971 Lehmann etal 260/8072 X 3,553,153 1/1971 Hazen et al........... 260/296 3,242,1233/1966 Mayfield et al.. 260/808 3,531,547 9/1970 Hazen et al......260/78.5 R 3,085,920 4/1963 Taylor et al. 161/232 3,669,727 6/1972Raymond 161/231 X Primary Examiner-Charles E. Van Horn Attorney-James E.Bryan [57] ABSTRACT This invention relates to a linear heat-hardenablecopolymerizate, and to a method of treating a wood surface with a foilof the said 'copolymerizate, the copolymerizate having a limitingviscosity of 1; 0.7 to 3.0 (100 ml g measured in toluene at 20 C., andcomprising seventy to 94 mole percent of a compound selected from thegroup consisting of styrene or at least one monomer having the formulain which R is selected from the group consisting of hydrogen and amethyl group, and R is an alkyl group having 1 to 4 carbon atoms,

two to 15 mole percent of at least one compound selected from the groupconsisting of maleic anhydride and itaconic acid anhydride, and four to15 mole percent of at least one compound selected from the groupconsisting of acrylic acid 'glycidyl ester and methacrylic acid glycidylester,

2 Claims, No Drawings LINEAR HEAT-HARDENABLE COPOLYMERIZATE This is adivision of application Ser. No. 31,748, filed Apr. 24, 1970, now US.Pat. No. 3,694,418.

This invention relates to novel linear heat-hardenable copolymerizatesand to the use thereof, preferably in the form of self-supporting foils,for improving the surfaces of raw materials, particularly sheets ofwood, by pressing the foils thereon at elevated temperatures.

Known to the art are various linear copolymerizates containing reactivegroups which are cross-linked at elevated temperatures with conversionof the thermoplastic copolymei'izate into an insoluble and infusiblepolymerizate.

U. S. Pat. No. 2,604,463, for example, describes a linear thermoplasticcopolymerizate obtained from acrylic acid glycidylester, acrylic acid,styrene, and acrylic acid methyl ester. The acrylic acid glycidyl esterand the acrylic acid are present together in the copolymerizate in aquantity such that, when the copolymerizate is heated, a sufficientcross-linking occurs. The quantity of the two aforementioned compoundsshould not, however, exceed per cent by weight, based upon the weight ofthe copolymerizate.

French Pat. No. 1,374,297, discloses the preparation of copolymerizatesof styrene, ethylacrylate, acrylic acid, and acrylic acid glycidyl esterin the form of an emulsion. Formed during the reaction are latticeswhich can be cross-linked after application and drying at temperaturesin the range of 100 to 150C.

U. S. Pat. No. 3,223,670, discloses copolymerizates of vinyl acetate,acrylic acid, itaconic acid, and acrylic acid glycidyl ester. Thesecopolymerizates also are obtained by emulsion polymerization attemperatures in the range of 55 to 60C.

U. S. Pat. No. 3,242,931, discloses the preparation of an adhesive forplywood consisting of a heathardenable copolymerizate obtained, forinstance, by emulsion polymerization of vinyl acetate, methacrylic acidglycidyl ester, and acrylic acid. A thickening agent is added to theresulting emulsion.

British Pat. No. 1,025,694, similarly disclosed hardenablecopolymerizates of acrylic acid ethyl ester, methacrylic acid glycidylester, and acrylic acid. It is disclosed in the patent that theseproducts are well suited for the treatment of surfaces.

The hardenable copolymerizates of the prior art are employed essentiallyas binding agents for stoving lacquers. Self-supporting foils based onsuch products, which would be suitable for the pressure coating of woodsheets, are not described. Actually, they would not have been consideredfor such use because of the hardenable conditions thereof, since theresidence time within the heated mold of the materials to be improvedwould have to be so long as to be prohibitive. This is undesirable notonly in view of the long time required, but because it may result indamage to delicate materials, such as wood sheets, which might bedamaged either mechanically or chemically by prolonged residence in themold while subjected to pressure and an elevated temperature.

The present invention provides linear heathardenable copolymerizateshaving relatively short hardening times yet possessing sufficientrheological properties to form pore-free and flawless surface protectivelayers at moderate pressure, particularly on sheets of wood materials,which protective layers moreover adhere well to such wood bases.

The copolymerizates of the present invention contain Seventy to 94 moleper cent of styrene or one or more monomers having the formula wherein Ris hydrogen or a methyl group, and R is an alkyl group having from 1 to4 carbon atoms,

Two to 15 mole percent of maleic anhydride and/or itaconic acidanhydride, and

Four to 15 mole percent of acrylic acid glycidyl ester and/ormethacrylic acid glycidyl ester.

The copolymerizate also may contain 0 to 3 mole percent of vinylpyridine. The copolymerizate has a limiting viscosity of 1 0.7 to 3.0 mlg") measured in toluene at 20C.

The structure of the copolymerizate may be recognized from essentiallythree specific types of monomers, i.e.:

1. Present in an excess amount, based upon the weight of thecopolymerizate, is a carrier monomer or a mixture of several carriermonomers. These carrier monomers are either alkyl esters or acrylic acidor methacrylic acid, wherein the alkyl residue of the alcohol employedfor the esterification has from 1 to 4 carbon atoms, or mixtures of suchacrylic acid and methacrylic acid esters or, instead of these esters,styrene may be employed.

Exemplary of the acrylic acid and methacrylic acid esters are methyl,esters, ethyl esters, propyl esters, and butyl esters.

2. Smaller portions of maleic anhydride and/or itaconic acid anhydride,as compared to the carrier monomer. The use of unsaturated cyclicdicarboxylic acid anhydrides as compounds capable of reacting withglycidyl groups constitutes an essential part of the present inventionsince these anhydrides effect the rapid hardening of the copolymerizatesand thereby render them useable for the intended application.

3. Acrylic and/or methacrylic acid glycidyl esters are employed asmonomers containing glycidyl groups.

It is possible to employ, as a fourth polymerization component, vinylpyridine in small quantities; it catalyzes the hardening process becauseof its basic properties and is built into the polymerizate by means ofits vinyl group.

Since the copolymerizates are designed particularly for improving 'thesurfaces of materials made from wood, it is necessary that thecopolymerizates, during heating thereof under pressure and prior tobeing completely hardened, have a sufficient rheological capacity inorder, on one hand, to become adequately bonded to the base whilesimultaneously forming a sealed surface, on the other hand. For thispurpose, it is necessary that the copolymerizates not exceed a specificmolecular weight. The novel linear heat-hardenable copolymerizates have,therefore, a limiting viscosity characterizing the molecular weight(Staudinger index of 0.7 to 3.0), measured in toluene at 20C.

Self-supporting foils made from the novel copolymerizates can be storedfor a practically unlimited time at normal temperatures. Yet, even underunfavorable conditions, for example when exposed to elevatedtemperatures during storage, the foils may be 3 4 stored for a length oftime corresponding to the constirring, cooling is effected to -5 to+20C., preferably sumption thereof. C., and the reduced portion of theinitiator, the

V W buffer, and the entire monomeric mixture are then In the course ofthe hardening of the linear added, wherebyapl-l value between 3 and willresult. copolymerizates at elevated temperatures, the carbox- 5 Then theperoxide, which previously was dissolved in ylic acid anhydride groupscontained in the polymeria small amount of carrier monomer, is added.Until zate react with the glycidyl groups with the formation completeconversion is attained, stirring is effected in of a three-dimensionalreticular structure. This crossan atmosphere of nitrogen. Aftercompletion of the relinking reaction can be illustrated in a simplifiedmanaction, the polymerizate is precipitated from the emulner as follows:sion with an excess of methanol. The reaction mixture A Y. cii.?T?H-Efif. f '7 cH2cH r-' ?Hcii l CH CHCl-l O-C=O O=C C=O C=O O=C C=O g I lO O (I) (I) O l +Heating (|:H2 (I:H 2 (:H2 CH2 CH2 O O O l I l O O OOCH2-CHCH2 O=C C=O O=C l l l I (II (I: 1&0 CHCHTCH2CH ..,CHCHTCH2(|:

ln this general structure, T signifies the carrier monois washed withwater and the remaining water is remer. moved insofar as possible bymeans of a filter press.

The preparation of the linear heat-hardenable The reaction product thusobtained is then incorpocopolymerizate is effected in known manner,while rated into various organic solvents and may be poured care must betaken to ensure that no cross-linking or at Out to films which hardencompletely at temperatures least no significant cross-linking occursduring the 00- between and under Pressurepolymerization. For thisreason, two polymerization The polymerlzatlon of the monomers Solventsprocesses h b fou d to b u ef renders possible the use of somewhathigher tempera- (a) p i l advantageous i l i l tures so that working canbe effected at temperatures ization at low temperatures, particularly inthe range of in the range of about 200 to The Solvent and the 0 to 20For the purpose f preparing the emulsion, diluent both should have thecapacity for dissolving the it is possible to employ conventionalemulsifiers among resulting polymerizate- Exemplary of Such Solventsare: which the f ll i are exemplary; sodium lauryl dioxane, methylenechloride, acetone, and mixtures of fate, sodium dodecyl diphenylsulfonate, polyethylene methylethyl ketqne or isopfopyl alcohol with nglycol isooctyl pheny] ether sodium alkyl acrylic poly Generallyspeaking, the weight ratio of the polymerrzether sulfonatea Sodium tetraN 1 (ljz dicarboxye able monomers to the solvent should beapprommatelythyl) N octa(kcyl sulfosuccinate, polyethylene glycol 3 to 4:1. Theknown polymenzation initiators, such as,

nonylphenyl ether, and polyethylene glycol tridecyl for example,azodiisobutyric acid nitrile, benzoyl percoho] ether oxide, cumenehydroperoxide, or cumene peroxide The emulsion polymerization may beperformed at y? z g in z h i g percent by controlled pH values, andsodium acetate, sodium hyh 2 upon t s g t e fi h t d en hos hate andsodium oxalate are articular] an 015 are ma e mm 6 nova mear ea j ibgffer Salts. p y hardenable copolymerizates, for example by dissolvingas oxides and hydroperoxides in combination with iron em o u aregobtained which we h (ll)-salts, ascorbic acid,and sodium formaldehydesulfb i p f th t t d d h h d or oxylate. The bivalent iron also may beemployed in the 235 a; i g i g g i g h form of the ethylene diaminetetraacetic acid complex. p p u n e range 0 120 to 160 C. preferably140C. and at a pressure of t bl d h d a: especlauy Su] 3 e perm e 15cumene y ropemx about 25 kg/cm yield hard, well adhering, completely Inconnection with the determination of the quamh transparent films WlllCllare resistant to dilute acids and ties of unsaturated monomericcompounds required for alkahes as as alcohol "i benzme' Theifillns dothe preparation of the copolymerizate, it should be not l or Swen onlyneghglbly under the action of chlorinated solvents. taken into accountthat, on the basis of the varying re- The invention will be furtherillustrated b ref activity and reaction velocity, the quantities of thereto the followih exam les in which a" an y f fl g actants in thereaction do not correspond exactly to the Wei ht g p p s are par 5 yquantities of the different compounds contained in the g polymerizate.The amounts to be employed are best determined on the basis of apreliminary test.

The emulsion polymerization preferably is carried parts of water arefreed from dissolved oxygen by out in the following manner: boilingunder nitrogen and are thereafter cooled to The emulsifier, dissolved inwater, is added to water 0C. Added thereto are 6 parts of sodium laurylsulfate which is free from oxygen as much as possible. While (dissolvedin 20 parts of oxygen-free water), 44 parts Example I of styrene, 4.4parts of acrylic acid glycidyl ester, and 1.7 parts of maleic anhydride.The mixture is homogenized and then added thereto, drop by drop, are 5parts of sodium acetate (dissolved in 5 parts of oxygen-free weight and8.8 per cent by weight, respectively. Also proven by the IR spectrum,aside from the anhydride and glycidyl groups, is a higher proportion ofcarboxylic acid groups. A film pressed upon wood does not swelling indexis 1.7 at a temperature of 150C. and minutes time. The gel content is100 percent. The acid anhydride and glycidyl group content is 3.4 percent by water), 1.2 parts of iron (ID-ammonium sulfate (dis- 5 displaythe brown coloration mentioned in connection solved in 5 parts ofoxygen-free water) and 0.28 part of with Example 1. The Buchholzhardness (DIN 53153) cumene hydroperoxide (dissolved in 2 parts of styis105. rene). During reaction, the temperature is constantly maintained at0C. After 40 hours, the emulsion is in- Example 3 troduced into 750parts of methanol; the precipitated 10 Following the procedure ofExample l,a series of expolymerizate is washed with water, againintroduced periments is performed in which varying quantities of into750 parts of methanol, and then filtered in a filter maleic anhydrideand acrylic acid glycidyl ester are empress. The yeild amounts to 95 percent of theoretical. played. Styrene is replaced by methacrylic acidethyl The Polymerizate is Soluble in benzene, toluene, methester, andsodium acetate is replaced by disodium hyylene chloride, methylethylketone and tetrahydrodrogen phosphate. f n-an. The Staudinger index intoluene at C. is n The following table shows the content of maleic an-2.76 (100 ml'g). Acid anhydride and glycidyl groups hydride and acrylicacid glycidyl ester in the monoare proven to be present qualitatively byinfra-red specmeric mixture; the reaction duration, the conversion,troscopy and quantitatively by titration with KOH and the Staudingerindex in xylene, the swelling index after pectively- The acid anhydridecontent is 3.3 20 heating at 180C. for 10 minutes, as well as the gelconper cent by weight, and the glycidyl content is 8.7 per tent aftercross-linking.

Acrylic acid Swelling Maleic glycidyl Duration Converindex ac- Gelanhydride ester reaction sion (100 ml-g cording to content (mole (mole(h) (20 C.) Dannenberg (70) cent by weight. The initial conversionvelocity of the As described in Example 1, the films are pressed;polymerization amounts to 15% h. they are transparent, hard, and show notension-fissure A film pressed upon wood at a temperature of 140C.corrosion after a prolonged treatment with methanol; for 15 minutes at apressure of 25 kg/cni is transparthey are not affected by dilute acidsand alkalies. The ent, has a Buchholz hardness (DIN 53153) of 100 andswelling in methylene chloride and ethyl acetate deis of a light browncolor. The adhesiveness is excellent. creases with an increasing contentof acrylic acid glyci- Corrosion due to a tension-fissure formationafter the 40 dyl ester. action of either methanol or ethanol-watermixtures does not occur. The hardened film is resistant to diluteExample 4 acid and alkalies, alcohol and benzine. Only a moder' 100parts of oxygen-free water are cooled to 0C., ate swelling occurs aftera 24-hour treatment with and added thereto are 5 parts of p-ter.-octylphenoxy methylene chloride or ethyl acetate. Film samples werepolyethylene glycol ether, 40 parts of methacrylic acid heated for 10minutes at 150C. and thereafter treated. methyl ester, 4 parts ofacrylic acid glycidyl ester, and with boiling chloroform: the gelcontent was found to' 6.1 parts of maleic anhydride. The mixture ishomogebe 100 percent. The swelling index according to H. nized and thenadded thereto, drop by drop, are 3 parts Dannenberg and W. R. Harp, Jr.,Anal. Chem. 28 ofdisodium hydrogen phosphate, 1.2 parts of iron (11)-(1956) 86 (determined after standing for 24 hours in ammonium sulfate(dissolved in 5 parts of oxygen-free a 1,2-dichloroethane atmosphere) is2.1. A film kept water) and 0.28 part of cumene hydroperoxide (disfor 3months at room temperature is actually slightly solved in 2 parts ofmethacrylic acid methyl ester). The cross-linked but, during pressing,still displays a good conversion after 6 hours is 93 percent oftheoretical. rheological capacity. The Staudinger index in chloroform at20C. is r 1.5 (100 ml g). The initial conversion velocity is 150% 1Example 2 -h The swelling index is 1.9 at 150 c. and 10 min- Theprocedure of Example 1 is repeated except that utes time. The gelcontent is 99 percent. The acid anhyemployed in the place of iron(ID-ammonium sulfate is dride content is 2.9 percent by weight; theglycidyl cona mixture of 0.1 part of sodium formaldehyde sulfoxytent is7.5 percent by weight. The IR spectrum is: anhylate, 0.015 part ofethylene diamine tetraacetic acid dride and glycidyl groups positive.and 0.75 part of iron (ID-chloride hydrate. The yield Films pressed uponwood at a temperature of 145C. after 24 hours is percent of theoretical.The initial for 10 minutes are transparent, hard, excellent withreconversion velocity is 17.5% h. The Staudinger spect to theadhesiveness thereof, have a Buchholz index in toluene at 20C. is n 2.3(100 ml g). The 65 hardness (DIN 53153) of 110, and are not affected bydilute acids and alkalies. After the action of methylene chloride andethyl acetate, a slight swelling occurs after 24 hours; test benzine hasno adverse effect. A film .employed instead of 40 parts of methacrylicacid methyl ester is a mixture of 20 parts of methacrylic acid methylester and 20 parts of methacrylic acid-n-butyl ester. Further, only 3.05parts of maleic anhydride are used. The conversion after 8 hours is 94percent of theoretical. The Staudinger index in chloroform at 20C. is n2.05 (100 ml g). The initial conversion velocity is 165% h. The swellingindex at 150C. and 10 minutes time is 2.1. The gel content is 100percent. The acid anhydride content is 2.8 percent by weight, and theglycidyl content is 7.4 percent by weight.

Films pressed upon wood at a temperature of 145C. for 10 minutes aretransparent, hard, excellent with respect to adhesiveness thereof, havea Buchholz hardness (DIN 53153) of 95, and are not affected by diluteacids and alkalies. Methylene chloride and ethyl acetate swell them onlyto a minor extent; test benzine has no adverse effect. No tensionfissure corrosionafter the action of methanol or ethanol-water mixturesis noted. A film stored for 3 months is still capable of flowing duringpressing.

Example 6 The procedure of Example 4 is followed with the furtheraddition, however, to the monomeric mixture of 1.8 parts of vinylpyridine. The conversion after 5 hours is 93 per cent. The initialconversion velocity is 160% h. The Staudinger index in chloroform at20C. is n 0.95. The swelling index is 1.9 at a temperature of 150C. and10 minutes time. The gel content is 100 percent. The acid anhydridecontent is 2.9 percent by weight, and the glycidyl content is 7.5 percent by weight. The IR spectrum shows anhydride and glycidyl groupspositive.

Films pressed upon wood at a temperature of 145C. for 10 minutes aretransparent, hard, excellent with respect to the adhesiveness thereof,have a Buchholz hardness (DIN 53153) of l 15, and are not affected bydilute acids and alkalies. After the action of methylene chloride andethyl acetate, only a minor amount of swelling occurs after 24 hours;test benzine has no adverse effect.

Example 7 Added to 100 parts of oxygen-free water at a temperature of C.are 6 parts of sodium lauryl sulfate (dissolved in 20 parts ofoxygen-free water), 50 parts of methacrylic acid butyl ester, parts ofacrylic acid glycidyl ester and 5 parts of itaconic acid anhydride. Themixture is homogenized and then added thereto, drop by drop, are 3 partsof disodium hydrogen phosphate, 1.2 parts of iron (ID-ammonium sulfate(dissolved in 5 parts of oxygen-free water), and 0.28 part of cumenehydroperoxide (dissolved in 2 parts of methacrylic acid butyl ester).The conversion after 8 hours is 90 percent of theoretical. The initialconversion velocity is 14% h. The Staudinger index in chloroform at 20C.is 1 0.90. The swelling index is 2.5 at 150C. and minutes time. The gelcontent is 96 percent. The acid anhydride content is 5.8 percent byweight, and the glycidyl content is 7.8 per cent by weight. The

' IR spectrum shows: anhydride and glycidyl groups positive.

Foils pressed upon wood at a temperature of 145C. for 10 minutes aretransparent, medium hard, well adhesive, have a Buchholz hardness (DIN53153) of 80, and are not affected by dilute acids and alkalies. Afterthe action of methylene chloride, ethanol, acetone and ethyl acetate, avery small swelling occurs after 24 hours; test benzine has no adverseeffect. The foil is resistant against tension-fissure corrosion.

Example 8 Added to parts of oxygen-free water at a temperature of 0C.are 5 parts of p-tert.-octyl phenoxy polyethylene glycol ether(dissolved in 20 parts of oxygenfree water), 20 parts of methylmethacrylate, 20 parts of ethyl acrylate. 4 parts of glycidyl acrylate,and 6.1 parts of maleic anhydride. The mixture is homogenized and thenadded thereto, drop by drop, are 3 parts of disodium hydrogen phosphate,1.2 parts of iron (11)- ammonium sulfate and 0.28 part of cumenehydroperoxide (dissolved in 2 parts of methyl methacrylate). Theconversion after 8 hours is 90 percent of theoretical. The initialconversion velocity is h. The Staudinger index in toluene at 20C. is 1;1.02. The swelling index is 2.9 at C. and 10 minutes time. The gelcontent is 98 percent. The acid anhydride content is 3.3 percent byweight and the glycidyl content is 8.0 percent by weight. The IRspectrum shows: anhydride and glycidyl groups positive.

Foils pressed upon wood at a temperature of 145C. for 10 minutes aretransparent, well adhesive, have a Buchholz hardness of 90, and are notaffected by dilute acids and alkalies. Acetone, ethyl acetate andethanol swell them only very slightly after a 24-hour treatment.

Example 9 200 parts of dioxane are freed from dissolved oxygen byboiling at reflux under nitrogen. Then added are 33.2 parts of methylmethacrylate, 10.7 parts of itaconic acid anhydride, and 6.1 parts ofglycidyl acrylate. The batch is stirred at a temperature of 20C. undernitrogen; initially added are 0.25 part and after 2, 4, 6 and 8 hours,0.05 part of azo-diiso-butyric acid nitrile (each 0.05 part beingdissolved in 2 ml of methylene chloride). The conversion after 67 hoursis 92 percent of theoretical. The Staudinger index in tetrahydrofuran at20C. is 17 0.5. The swelling index is 1.0 at 150C. for 10 minutes time.The gel content is 99 percent. The acid anhydride content is 9.8 percentby weight and the glycidyl content is 13.8 per cent by weight. The IRspectrum shows: anhydride and glycidyl groups positive.

Foils pressed upon wood at a temperature of 145C. for 10 minutes aretransparent, well adhesive, have a Buchholz hardness (DIN 53153) of 115,and are unaffected by dilute acids and alkalies, by test benzine andethanol. Methylene chloride, ethyl acetate and acetone cause only slightswelling after a 24 -hour treatment.

Example 10 Added to 200 parts of oxygen-free methylene chloride are 33.2parts of methyl methacrylate, 4.6 parts of maleic anhydride, and 12.2parts of glycidyl acrylate. Thereafter, stirring is effected undernitrogen at 40C., and then added are initially 0.25 part, andthereafter,

after 2, 4, 6 and 17 hours, a 0.05 part quantity of a20- diisobutyricacid nitrile. The conversion after 80 hours is 86 percent oftheoretical. The Staudinger index in tetrahydrofuran at 20C. is 17 0.62.The swelling index is 1.9 at 150C. and 10 minutes time. The gel contentis 98 per cent. The acid anhydride content is 2.6 per cent by weight andthe glycidyl content is 19.3 percent by weight. The IR spectrum shows:anhydride and glycidyl groups positive.

Foils pressed upon wood at a temperature of 145C. for 10 minutes aretransparent, adhesive, have a Buchholz hardness (DIN 53153) of l 10, andare unaffected by dilute acids and alkalies. Methylene chloride, ethylacetate and acetone cause only minor swelling after a 24-hour treatment.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the tions.

What is claimed is:

1. An improved wood surface having a foil of a linear heat-hardenablecopolymerizate having a limiting viscosity of 'r)=0.7 to 3.0 ml 'g')measured in tolu-. I

glycidyl ester and methacrylic acid glycidyl ester.

2. A wood surface according to claim 1 in which the copolymerizateincludes, in addition, not in excess of 3 mole percent of vinylpyridine.

UNITED QS'ZFATESQPATECNTOFFHCE QE'ElFlQ-ATE P so MUN Patent No.3,767,522 Dated October 2,3, 1973 l l Inventofls) Iilrgen Pock et a1patent I v It is certified that error appears in the above-identifiedand that said Letters Patent are hereby corrected asshown below Coveringpage, Ite r n 75 "Iurgen Foch" should reac io v 1 Iurge n Pock-=---.lColumn 1, line 43, '"disclose cl" should read} discloses Column 5,.1ine13, "yeild" should readyield Column 10,1ine 4, sffef "oopolymefi zetej".tl'leffollowing should. be.

inserted 4 bonded thereto, the copolyirnellzalze'f+5};

Signed enclsealed this 119th dfay 19714,, T

(sEAL) Atte st c, M RS ALL- DANN "Commissioner of Patents EDWARDM@FLETGlER,JR. Attesting Officer F'QRM PO-JGEO (TU-69)

2. A wood surface according to claim 1 in which the copolymerizate includes, in addition, not in excess of 3 mole percent of vinyl pyridine. 